Dielectric filter, duplexer, and communication apparatus incorporating the same

摘要

A dielectric filter in which many attenuation poles can be generated, including attenuation poles generated by tap coupling, so that arbitrary passing characteristics and attenuation characteristics can be obtained. In this filter, inside a dielectric block there are formed through-holes having stepped structures in which inner conductors are disposed on the inner surfaces of the holes to capacitively couple the resonators. There are also formed lateral holes having conductive films disposed on the inner surfaces of the holes. The lateral holes are connected to input/output terminals in predetermined positions of the inner conductors. Further, terminal electrodes may be disposed adjacent to predetermined positions of the inner conductors. With this arrangement, attenuation poles are generated by both distributed constant resonator coupling and tap coupling on the low frequency side and/or the high frequency side of a pass band.